The long term objectives are to characterize the surface antigens expressed by Candida albicans during in vitro and in vivo development, determine if monoclonal antibodies raised against these antigens may be used to biotype strains of C. albicans, and extract and chemically characterize antigens which may be important in pathogenesis. The first objective will be done by establishing a bank of monoclonal antibodies specific for surface antigens of C. albicans and use these in conjunction with immunocolloidal gold electron microscopic techniques. The second objective will entail reacting the antibodies with many strains of the fungus grown under specified conditions. The third objective will be done by using mutants to identify pathogenetic determinants and monoclonal antibodies to purify the antigens from cell wall extracts. To induce antibody responses to many surface antigens, mice will be immunized to a variety of cell wall and other subcellular fractions. Some cell wall fractions will be enriched for hyphal- specific antigens. Specificities of monoclonal antibodies resulting from fusions of sensitized spleen cells with plasmacytoma cells will be determined by crossed immunoelectrophoretic techniques. The various antibodies will be used to detect antigen expression among many isolates of C. albicans and other yeasts to determine if the antibodies could be used for biotyping C. albicans strains. In addition, characterization of antigen expression on selected strains will be done by following yeast and hyphal development in vitro and in vivo at the level of electron microscopic analysis. These studies will provide comprehensive knowledge concerning the stability or variability of candidal antigen expression during development of cadidiasis in a murine model of this disease. A bank of monoclonal antibodies to the various antigens will be developed as a result of this work and these antibodies will be used to select mutants unable to produce a particular surface determinant. Virulence of these mutants will be tested in mouse models of candidiasis to ascertain which antigens may be related to the ability to cause disease. Such antigens will be isolated from wild type strains and chemically characterized.